Scientific Forecaster Discussion
fxus63 kiwx 130039
Area forecast discussion
National Weather Service northern Indiana
739 PM EST Tue Nov 12 2019
issued at 533 PM EST Tue Nov 12 2019
In the wake of the first significant snow and lake effect event
of the season, record cold temperatures will grip the area. Low
temperatures will plunge into the single digits above to single
digits below zero by daybreak Wednesday. Highs Wednesday afternoon
will only reach the middle to upper 20s. A weak system may provide
light snow Wednesday night, primarily north of Route 6. A very
gradual warming trend will bring temperatures back to upper 30s
and lower 40s by the weekend.
Short term...(this evening through wednesday)
issued at 338 PM EST Tue Nov 12 2019
Final death kneel in epic lake effect event as dry air continues
whittle cloud layer depth from above and below through the
remainder of evening hours. Little additional accumulation in
isolated areas within heart of middle 20s dbz cells. Otherwise,
the primary concern lies with overnight low temperatures amid
fresh snowpack. Suspect model derived temperatures greatly
underplaying albedo effects given strong performance of event
with 30-40 to 1 snow liquid ratios. Have markedly lowered
temperatures in anticipated solid boundary layer decouple. Only
concern will be rapid advance of mid level moisture/warm air
advection in advance of weak clipper system dropping out of
eastern Montana into the plains. Leading altocumulus deck should
be thin/high/late enough into the region to preclude an early halt
to temperature falls. Given cold start and energy needed to
debride snowpack have undercut highs Wednesday afternoon, albeit
to lesser extent.
Long term...(wednesday night through tuesday)
issued at 739 PM EST Tue Nov 12 2019
Clipper system weak and markedly limited with dry subcloud
region, especially across southern half of County Warning Area. Limited light
amounts, primarily north of Route 6. Suspect an eventual strong
north to south pop/qpf/snowfall gradient resolution as event
nears. Otherwise rather benign period with broad/shallow Continental U.S.
Trough persisting and surface ridge slowly migrating eastward held
up by weekend cyclogenesis off eastern Seaboard.
Aviation...(for the 00z tafs through 00z Wednesday evening)
issued at 1144 am EST Tue Nov 12 2019
VFR/dry this period as sfc ridge shifts east through the Ohio Valley.
Lm...Small Craft Advisory until 11 PM EST this evening for lmz043-046.
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